PROJECT SUMMARY While modern HIV combination therapy has transformed HIV into a manageable chronic infection for many patients, HIV/AIDS remains a formidable global epidemic. Despite the effectiveness of combining drugs from different classes, side effects and drug resistance remain serious concerns for these life-long therapies. Thus, there is an enduring need for novel HIV inhibitors with new mechanisms of action and stronger barriers to resistance. Furthermore, it is recognized that lack of patient compliance is a major factor leading to treatment failure. For this reason, HIV specialists are excited by the prospect of long-acting therapies, and a combination of such therapies would provide a revolutionary new treatment option for many HIV patients. Navigen is a small pharmaceutical company targeting infectious diseases through an innovative discovery and design process. We have identified a novel HIV entry inhibitor, cholesterol-PIE12-trimer (CPT31), that is a protease-resistant D-peptide (peptide made from D-amino acids) that targets HIV?s conserved entry machinery. With highly potent activity against all major HIV subtypes, designed barriers to resistance, and in vivo animal efficacy, our anti-HIV D-peptide overcomes the current limitations of the entry inhibitor treatment class. Additionally, CPT31 is ideal for pre-exposure prophylaxis (PrEP) since it blocks the first stage of the viral lifecycle prior to infection of target cells. Navigen has advanced CPT31 to late preclinical development via a recently completed Phase II SBIR award. In this three-year SB1 application we will complete 1) GMP manufacturing of drug substance, 2) GMP formulation of drug product including stability testing and aseptic packaging, 3) IND-enabling animal toxicology, and 4) our IND package. These studies will exclusively advance a daily-dosing formulation that will be used to establish the safety of our D-peptide therapeutic in animals and humans. However, CPT31?s high potency, protease resistance, and favorable pharmacokinetic (PK) and physicochemical properties make it an ideal candidate for extended-release depot formulation. In parallel with the studies proposed here, we are working with extended-release formulation experts to develop a long-acting formulation of CPT31 (CPT31-LA) suitable for once-monthly (or less frequent) injection. Many patients prefer long-acting injectables to daily oral pills. Therefore, CPT31-LA will likely achieve broad market penetration. Achieving IND status will greatly facilitate the early investment needed to demonstrate human efficacy with CPT31 and, ultimately, a licensing agreement with a large pharmaceutical company who can bring CPT31-LA to market as a potentially transformative new option for the prevention and treatment of HIV.